This invention generally relates to improvements in a spring seating support system for upholstered furniture. This invention is particularly well suited for use as a spring seating support system in sofas, love seats, chairs, and similar furniture. Although the present invention is in no sense limited to upholstered furniture, the herein illustrated forms which the present invention may take are particularly adapted for use in upholstered furniture. For this reason, the objects and advantages hereinafter disclosed will have specific reference to upholstered furniture, but such objects and advantages are intended to extend to other types of construction wherein any one of the desired characteristics of the spring seating support system would be advantageous.
Conventional box springs for upholstered furniture are comprised of a lower wooden or wire support frame and an upper support system. Between the upper support system and the lower support frame there are a plurality of coil springs which are generally helical or cylindrical coil springs. To insure that the axis of each of the coil springs remains vertical, each spring must be secured to both the upper support system and to the lower support frame.
Coil springs are typically aligned in successive rows in such a fashion that the coil springs are substantially aligned with corresponding coil springs in the adjacent row. Thus, the coil springs are aligned in spaced columns and rows. Presently, there is no standard in the industry regarding the spacing of the coil springs in rows or columns.
The edge of a conventional box spring unit is flexible because the padding and upholstery are directly covering the coil springs, which are flexible. The flexibility of the edge of a conventional box spring, however, complicates the manufacturing process at the stage when the padding and upholstery are applied because it is difficult to securely fasten the padding and upholstery to a nonrigid surface. In addition, the movement of the flexible coil springs when they are compressed under weight or pressure acts to loosen the padding and upholstery over time and thereby to reduce the effective life of the conventional box spring unit.
A conventional hard edge spring seating unit does not have these concerns. Conventional hard edge springs seating units have a hard front edge which allows for padding and upholstery to be attached in a secure manner. Conventional hard edge seating units, however, use sinuous springs to support the weight or pressure applied to the top of the unit. Sinuous springs do not provide as comfortable a level of support as do coil springs because each sinuous springs is sensitive to the movement of the other sinuous springs, and interference between sinuous springs leads to unsteady distribution of the weight or pressure.
The spring seating support system which is the subject of this invention provides the comfortable support of coil springs with the durability and ease of manufacture associated with a hard edge. It uses a flexible wire grid to link the coil springs and the hard front edge. This allows the coil springs to compress under weight or pressure while they are joined to the rigid hard front edge without damaging the connecting wire grid. The wire grid is able to pivot at the attachment point with the hard front edge, so that it can properly keep the coil springs aligned along the vertical axis while maintaining contact with the hard front edge so that the padding and upholstery are able to lie flat. In this way, the spring seating support system which is the subject of this invention provides the benefits of a hard front edge to which padding and upholstery can easily and durably be attached during the manufacturing of the unit and of a coil spring support system which allows for comfortable support of weight or pressure.